Tests for an end-of-sample bubble in financial time series

ABSTRACT

In this paper, we examine the issue of detecting explosive behavior in economic and financial time series when an explosive episode is both ongoing at the end of the sample and of finite length. We propose a testing strategy based on a subsampling method in which a suitable test statistic is calculated on a finite number of end-of-sample observations, with a critical value obtained using subsample test statistics calculated on the remaining observations. This approach also has the practical advantage that, by virtue of how the critical values are obtained, it can deliver tests which are robust to, among other things, conditional heteroskedasticity and serial correlation in the driving shocks. We also explore modifications of the raw statistics to account for unconditional heteroskedasticity using studentization and a White-type correction. We evaluate the finite sample size and power properties of our proposed procedures and find that they offer promising levels of power, suggesting the possibility for earlier detection of end-of-sample bubble episodes compared to existing procedures.     

Connecting through chaos: escape behaviour among sex-working adolescents in Aotearoa New Zealand

Underage sex work (USW) has been shown to adversely affect adolescents’ physical and psychological wellbeing; however, little is known about the lives of sex-working adolescents or their needs for services. This study involved semi-structured interviews with eight adolescents who began sex work between the ages of 12 and 16. It was found that caregivers’ characteristics, attachment disruption and early trauma intersected with participants’ wider social environments, specifically with their peer relationships and limited access to services, to create a culture of chaos and avoidant coping. These combined factors constitute significant barriers to service access, and require considered navigation of relational and environmental barriers as well as appropriate management of psychological distress and trauma symptoms to enable effective engagement with services.     

Building protest online: engagement with the digitally networked #not1more protest campaign on Twitter

This article examines engagement with digitally networked, politically contentious actions. Maintaining engagement over time is a key challenge for social movements attempting to network digitally. This article argues that proximity serves as a condition to address this challenge, because it configures the personal networks upon which transmission depends. This is a paradox of digital activism: it has the capacity to transcend barriers; however, proximity is essential for sustaining relations over time. Examining Twitter data from the #not1more protest campaign against immigrant deportations in the United States, quantitative and social network analyses show a differentiated development of engagement, which results in a particular geographical configuration with the following attributes. First, there is a robust and connected backbone of core organizers and activists located in particular major cities. Second, local groups engage with the campaign with direct actions in other cities. Third, a large and transitory contingent of geographically dispersed users direct attention to the campaign. We conclude by elaborating how this geographically differentiated configuration helps to sustain engagement with digitally networked action.     

Child and Household Deprivation: A Relationship Beyond Household Socio-demographic Characteristics

This paper aims to contribute to the literature on poverty and social exclusion by analysing the type of deprivation of the household where the child lives and the level of deprivation that child experiences. Using the EU-SILC 2009 module on deprivation for Spain, we find that the level of child deprivation varies among household types, that is, even after controlling for the socio-economic characteristics of the household and parents, the lack of certain items at the household level induces a more intense child deprivation. Therefore, we can conclude that there exists an association between child deprivation and the household deprivation profile that surpasses the socio-demographic characteristics of the household and parents.     

Maternal singing of lullabies during pregnancy and after birth: Effects on mother–infant bonding and on newborns’ behaviour. Concurrent Cohort Study

Background

Mother–infant bonding is of great importance for the development and the well-being of the baby. The aim of this Concurrent Cohort Study was to investigate the effects of mothers singing lullabies on bonding, newborns’ behaviour and maternal stress.

The effects of a workplace intervention on employees’ cortisol awakening response

Work-related stressors are known to adversely affect employees’ stress physiology, including the cortisol awakening response (CAR) – or the spike in cortisol levels shortly after people wake up that aids in mobilizing energy. A flat or blunted CAR has been linked to chronic stress and burnout. This daily diary study tested the effects of a workplace intervention on employed parents’ CAR. Specifically, we tested whether the effects of the intervention on CAR were moderated by the type of days (workday versus non-work day). Data came from 94 employed parents from an information technology firm who participated in the baseline and 12-month diurnal cortisol components of the Work, Family, and Health Study, a group-randomized field experiment. The workplace intervention was designed to reduce work-family conflict (WFC) and implemented after the baseline data collection. Diurnal salivary cortisol was collected on 4 days at both baseline and 12 months. Multilevel modeling revealed that the intervention significantly increased employees’ CAR at 12 months on non-workdays, but this was not evident on workdays or for employees in the usual practice condition. The results provide evidence that the intervention was effective in enhancing employees’ biological stress physiology particularly during opportunities for recovery that are more likely to occur on non-work days.     

How leader humility helps teams to be humbler,psychologically stronger,and more effective: A moderated mediation model

We hypothesize that (a) the level of humility expressed by leaders predicts team performance through, serially, team humility and team PsyCap, and (b) the strength (i.e., consensus within the team) of the leader humility, team humility and team PsyCap moderates the paths of that hypothesized model. A sample comprising 82 teams (82 leaders; 332 team members) was collected. Team members reported leader humility, team humility and team PsyCap. Leaders reported team performance. To handle the risks of common method bias, each mediating path of the hypothesized model is based on data from two different subsamples within each team. Our model's most novel theoretical contribution is the (moderated mediated) connection between leader humility, collective humility, and team PsyCap, and this was consistently supported in our data. Our inconsistent findings dealing with the relationship between team PsyCap and performance is well established in the literature and our results in both sub-samples were in the theorized direction. The study contributes to understand why, how and when humble leaders are more effective.